1. Field of the Invention
The present invention relates generally to harsh environment connectors such as wet mate connectors which can be mated and unmated in a wet environment such as underwater and which are exposed to a harsh working environment, such as seawater.
2. Related Art
There are many types of connectors for making electrical and fiber-optic cable connections in hostile or harsh environments, such as undersea connectors which can be repeatedly mated and demated underwater at great ocean depths. These connectors typically consist of plug and receptacle units or connector parts, each attached to cables or other devices intended to be joined by the connectors to form completed circuits. To completely isolate the contacts to be joined from the ambient environment, one or both halves of these connectors house the contacts in oil-filled, pressure-balanced chambers.
Both the plug and receptacle halves of most fiber-optical connectors which are mateable in a harsh environment have oil-filled chambers. The chambers are typically brought face-to-face during an early step of the mating sequence. In a subsequent mating step, one or more connective passages, sealed from the outside environment, are created between the chambers of the mating connector halves. The passages join the two oil-filled chambers, creating a single, connected oil volume. Actual connection of the contact junctions then takes place within the common oil chamber. There are several patented examples of such connectors, such as U.S. Pat. Nos. 4,682,848; 5,738,535; 5,838,857; 6,315,461, and 6,736,545.
Some such existing connectors work very well. The technology is relatively new, however, and there is still much room for improvement. In particular, the existing products are complex, expensive, and their reliability is not flawless.
One major problem in designing such connectors for mating in an undersea environment or other harsh environments is the provision of seals which will adequately exclude seawater and other contamination from the contact member even after repeated mating and demating, and also prevent fill fluid from leaking out of the chamber.
A number of different sealing mechanisms have been proposed in the past for achieving this objective. One such sealing mechanism has an opening into the contact chamber which comprises an elastomeric tubular entrance surrounded by an elastomeric sphincter which pinches the entrance closed upon itself when the plug and receptacle units are in an unmated condition. On mating, the contact probe is forced through the opening and the sphincter pinches against the probe to form a seal. Although this type of seal is successful in some cases, it does have disadvantages. One disadvantage is that this seal does not work well under all hostile conditions. Another disadvantage is that such seals tend to lose their “memory” after repeated mating and demating, so that they may fail to close completely, or may not close quickly enough to isolate the chamber from the surrounding environment when the units are demated.
Another type of known seal mechanism comprises a piston which moves axially into the seal opening as the units are demated. In some known underwater electrical connectors, such as that described in U.S. Pat. Nos. 4,795,359 and 5,194,012 of Cairns, tubular socket contacts are provided in the receptacle unit, and spring-biased pistons are urged into sealing engagement with the open ends of the socket assemblies. As the plug and receptacle units are mated, pins on the plug portion urge the pistons back past the contact bands in the sockets, so that electrical contact is made. However, this type of arrangement cannot be used in a straightforward way for an optical connector since the optical contacts must be able to engage axially for practical purposes.
Another line of wet-mateable connectors is of the type as described in U.S. Pat. No. 6,736,545 of Cairns et al., for example. The patent discloses a wet-mateable connector comprising first and second connector portions movable between unmated and mated positions. In addition, the connector also includes first and second bladders in respective connector portions and cooperating therewith so that opposing ends of the bladders are sealably urged together and moved from a closed to an open position as the connector portions are moved from the unmated to the mated position. One possible disadvantage of such connectors is that the shape of the opening in the ends of the bladders may not be large enough when open to use higher fiber counts, for example.
Therefore, what is needed is a system and method that overcomes these significant problems found in prior wet mate connectors as described above.